Cervical Cancer: Screening

by Christine Haran

January is Cervical Cancer Awareness and a time to recognize that cervical cancer is one of the few preventable cancers, thanks to a highly effective screening test discovered by George Papanicolau, MD, in the 1950s.

"We forget that, in the 1940s and earlier, cervical cancer was a very common cancer in the United States," says Alan G. Waxman, MD, an associate professor of obstetrics and gynecology at the University of New Mexico School of Medicine in Albuquerque. Since the Pap test was first introduced, the cervical cancer rate has dropped by roughly 50 percent. But the rate is still high among minority and low-income women, who are not screened regularly.

In the last few years, new cervical cancer screening tests have been developed and new guidelines for cervical cancer screening have been released. While the new tools will help some women, studies show that most women diagnosed with cervical cancer today are those who have never been screened for it. Below, Dr. Waxman, who cowrote the American College of Obstetrics and Gynecology (ACOG) guidelines, discusses the new technologies and recommendations.

What are the primary risk factors for cervical cancer?

Cervical cancer is sexually transmitted and this has been known for a long time. What has only been appreciated over the last 10 to 15 years is that cervical cancer is caused by the human papilloma virus, or HPV.

The risk factors for cervical cancer are therefore the same as the risk factors for acquiring a sexually transmitted disease, so women who have multiple partners are more likely to come in contact with the virus. And because of the nature of the cervix, the cervix is more susceptible to HPV when women are young. Therefore, women who initiate sexual intercourse in adolescence, which is when most women in the United States do, are at increased risk.

The virus is necessary but not sufficient to cause the cancer. Which is to say, lots of women get HPV and, in most cases, their immune system gets rid of it, or at least clears it to levels that are too low for us to detect with the available technologies.

While the exposure and acquisition of the virus is necessary, the development of cervical cancer requires other factors. For instance, women who are transplant patients, who are on corticosteroid medications long-term or who have HIV are at increased risk because their immunity is suppressed.

The other thing that increases risk is smoking. Smoking seems to reduce the ability of the cervix to fight off this infection, and there have been a number of studies that show that when a woman smokes a cigarette, nicotine and the nicotine metabolites are concentrated in the cervical mucous. I always remind my patients that this is one more excellent reason to stop smoking.

Getting Pap smears on a regular basis is the principle way to bring down the cervical cancer rate, so not having access to screening is a significant risk factor. For instance, among the Lakota Indians in North and South Dakota, cervical cancer screening is not widespread. And smoking is also more prevalent in that population. So they have a much higher rate of cervical cancer and precancerous changes.

Why has the Pap test been such a good screening test?

It's an ideal screening test for a number of reasons that you could pull right out of a textbook of public health. It deals with a disease that, in the absence of the screening, is very common. Cervical cancer is the second-most common cancer among women in the world.

Number two, treatment exists once the disease is identified. Number three, it's a disease that has a very long latent period. What that means is that a woman may develop one of the precursor lesions and not develop cancer for 10 or 15 years. And that gives us numerous opportunities to intervene and prevent cancer.

Finally, the Pap test is inexpensive and it's a test that's acceptable to the general population. By comparison, if we look at screening for colon cancer, colonoscopy and sigmoidoscopy are not all that acceptable to the general population. Those are moderately uncomfortable, time-consuming and expensive procedures, and as a result they haven't been as accepted by the general population.